Answer:
The answer is below
Explanation:
The half life of a substance is the time required by that substance to reduce to half of its initial value. The half life is calculated using the formula:

Given that t = 87 years, half life = 29 years, therefore the quantity of strontium-90 left is:

That is one-eight of Strontium 90 would be left after 87 years
No this is false sinking of dense, cold water with high salinity
The moon has phases because of where the sun shines on it. Only yhe part wiyh light of the moon is visible. As the moon moves, the sun light hits is at different angles and creates the different shapes we call phases.